It has been widely practiced to add an inorganic filler to a synthetic resin for the improvement of the mechanical characteristics of the synthetic resin moldings, the reduction of the raw material cost, etc.
However, when a large amount of an inorganic filler is added to a synthetic resin, the inorganic filler is difficult to disperse which thereby greatly reduces the moldability and, sometimes, extremely reduces the mechanical characteristics of the moldings obtained. This is considered to be caused by the poor affinity of the synthetic resin for the inorganic filler.
Hitherto, for solving such a disadvantage, it has been attempted to improve the affinity of a synthetic resin for an inorganic filler using a coupling agent such as a fatty acid, fatty acid salt, fatty acid ester, and titanate, as described in U.S. Pat. No. 4,812,282.
However, by conventional methods, the improved effect of the affinity of a synthetic resin for an inorganic filler is still insufficient, the addition amount of an inorganic filler is restricted, and the reduction of mechanical characteristics is unavoidable.